If it takes a prince to alert the nation to the safety-valve powers of boxing in coping with mental stress – as Prince Harryhas done this week – Frank Bruno, who has rubbed shoulders with royalty and struggled with mental health issues, will surely lead the applause.

The former world heavyweight champion, now 55, has been sectioned three times since he retired in 1996 and came perilously close to being institutionalised for life. He has suffered more through mental trauma than from any bruises to body or spirit absorbed in 45 bouts over 14 years as a professional boxer. Paradoxically, he says boxing has also saved him.

Boxing, despite its long history of tragedy and corruption on the professional side – from ring deaths to Mafia fixes – has attracted a growing constituency of keep-fit devotees in hundreds of gyms around the country, among them the singer Ellie Goulding. “It wasn’t about any change in my outward appearance,” she said last month when talking about how working out in a boxing gym helped her cope with anxiety. “It was about seeing and feeling myself get better and stronger... I truly feel that exercise – however you like to work out – is good for the soul.”

It is a sentiment echoed by Harry, who says he found refuge in the gym when the weight of his mother’s premature death 20 years ago had pushed him, “very close to a complete breakdown on numerous occasions”.

Princess Diana’s youngest son, now 32, revealed: “During those years I took up boxing, because everyone was saying boxing is good for you and it’s a really good way of letting out aggression. And that really saved me because I was on the verge of punching someone; so being able to punch someone who had pads was certainly easier.”

While that entry-level introduction to the sport is some way distant from the rigours of boxing that Bruno endured, he would recognise the process.

Bruno has done much to raise awareness of bipolar disorder and it took a lot for him to admit that the effects of his illness were exacerbated as much by the mental as well as the physical demands of his trade.

Bruno said he had never felt so alive as in the immediate aftermath of winning the title against Oliver McCall in London in 1995. Nor had he ever been so alone: on top of the world at last after three failed attempts – but not for long, he suspected. In a nerve-racking defence against Mike Tyson five months later, Bruno surrendered his hard-won credibility inside three rounds.

In defeat, his marriage broke up and he was committed to a month’s treatment in the Goodmayes Clinic in Essex. It took his own iron resolve to continue the process in the gym, with the prize not a world title but his mental wellbeing. Bruno’s struggle is an ongoing one, aided by prescription medication and, pointedly, in the light of Prince Harry’s experience, a life-time commitment to exercise.